Bunch of SPAM threads on 1st post. How to stop?

[Gutspiller]

I am looking for a modification that will allow me to somehow block spam posts. Either from making a user go a certain amount of days before posting a url, or can only post in certain forums for the first amount of days or something to keep people from registering and making their first post about some MTV shit and then never returning. I think my forum is on some MTV ad companies forum list because we get one almost every week if not more frequent.

Can somebody please help me on where to look for something that can help with this problem? I would really appreciate any help someone can provide me with.

Thanks!